In addition to characteristic fatty acid methyl esters (FAMEs), biodiesel produced from Isochrysis sp. contains a significant amount (14%, w/w) of predominantly C37 and C38 long-chain alkenones. These compounds are members of a class of lipids known collectively as polyunsaturated long-chain alkenones (PULCAs) that are produced by a range of other prymnesiophyte taxa. The physical properties of alkenones, such as high melting points (60 °C), renders the direct product unsuitable for use as a diesel fuel but, nonetheless, represents an important and as yet unexplored renewable carbon feedstock.